1969

6.1

1975

5.5

1972

6.2

1974

5.8

1973

5.7

1971

6.1

1966

6.5

1965

6.2

1965

6.5

1978

6.5

1967

6.5

1965

6.7

1975

5.5

1980

7.1

1970

5.7

1970

6.2